partition package:utility-ht

partition :: (a -> Bool) -> [a] -> ([a], [a])
utility-ht Data.List.HT
partition of GHC 6.2.1 fails on infinite lists. But this one does not.
partitionMaybe :: (a -> Maybe b) -> [a] -> ([b], [a])
utility-ht Data.List.HT
Partition a list into elements which evaluate to Just or Nothing by f. 
forAllMaybeFn $ \f xs -> partitionMaybe f xs == (mapMaybe f xs, filter (isNothing . f) xs)

forAllPredicates $ \p xs -> partition p xs == partitionMaybe (\x -> toMaybe (p x) x) xs